In recent years, in accordance with progress of printer functions, it is possible to perform printing with respect to various products. Especially, by virtue of progress of ink jet printers, it is possible to perform printing with respect to products in various shapes. Since an ink jet printer discharges and attaches ink to a printing object, it is possible to perform printing even when the printing object has some irregularity on its surface.
However, even when this ink jet printer is used, it is not possible to print an image with respect to a bent part having a large amount of curvature such as a head band of a headphone. When printing is to be performed on such head band, the end of the head band is away from an ink discharge part and a printing object surface is slanted with respect to an ink discharge direction. Accordingly, it is impossible to appropriately and finely print an image on it.
As a method of printing an image with respect to such bent part having a large amount of curvature, a method of attaching an image using a seal, a method of pad printing (e.g., see Patent Literature 1), heat transfer printing and the like may be used.
However, the method of attaching an image using a seal is not a method of printing an image, and has a crucial failing. Since the seal is peeled off due to deterioration over time, the part is unclean.
Further, in the method of pad printing, it is not possible to print an image on a bent part by color printing. The pad printing is to transfer a print pattern on a pad transfer surface made of rubber material and press the transfer surface against a printing object so as to transfer the print pattern on the printing object surface. Therefore, according to this pad printing, it is possible to print an image on a printing object surface in a curved surface shape. However, in this pad printing, only monochrome printing using one sort of ink is possible, and it is not possible to realize color printing by the pad printing.
Further, in the printing by thermal transfer, when a printing object is made of a material which is not tolerant to high temperature such as resin, the method cannot be used since the printing object is melt by heat.